Attention!!! Do not carelessly grope the mainboard surface!

A novice tv technician comes with an LG motherboard that uses XD6481. According to him, the symptoms initially out the old picture. Then he fingered all the little ic (this is because based on the experience he used to do when fixing the tube tv). Sudden out a small fire on the middle of the mainboard.
Why can this happen?
Mainboard is usually equipped with some ic circuit called DC-DC step down converter. This circuit serves to lower the voltage of the input adapter 19V into 5v, 3.3v, or 1.8v.
The decrease in the magnitude of the voltage is generally determined by the value of the feedback resistor from the output voltage to the ic.
Our fingers can react as resistors with hundreds of ohms, but if we are sweating it can be even lower.
While groping the mainboard if the accidental coincidence is right on the resistor's feedback part then it could happen the output voltage soared ...
It is this kind of event that can cause XD's ic to burn.

Picture sample feedback on DC-DC ic type AZ1117-A

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